1. Field of the Invention
The present invention generally relates to a method for forming a gate electrode of a semiconductor device, and more specifically, to a method for forming a gate electrode of a semiconductor device wherein a nitride hard mask layer is deposited and subjected to an additional surface treatment process whereby a lattice structure of a nitride film surface becomes more dense so as to reduce an etching rate of the hard mask layer during the formation process of a gate electrode, and increase a thickness of the residual hard mask layer.
2. Description of the Related Art
In accordance a conventional method for forming a gate electrode of a semiconductor device, a gate oxide film, a polysilicon layer, a metal layer and a hard mask layer are sequentially formed, an anti-reflection film is formed on a surface of the hard mask layer, and a photoresist film pattern defining a gate electrode region is formed. Thereafter, the hard mask layer is etched using the photoresist film pattern as an etching mask to form a hard mask layer pattern. The metal layer, the polysilicon layer, and the gate oxide film are then etched using the hard mask layer pattern as an etching mask to form a gate electrode of a semiconductor device.
In accordance with the above-described conventional method for forming a gate electrode of a semiconductor device, as the thickness of the residual hard mask layer becomes increased after the formation of the gate electrode, a margin of a SAC process is improved during an etching process of a landing plug contact hole. However, when the deposition thickness of the hard mask layer is increased, a line width of in the gate electrode a peripheral circuit region is increased and deformed.